Need help with youtube background pic

so i need help getting a background picture to fit perfectly with a youtube account i had just made a few weeks back. I’m not sure what dimension i need but i dont really like the repeat image feature and the image looks way too enlarged. supposedly the image is supposed to be at least 256k in file size.

this is the image which is the pink ssf4 ae desktop that was released not to long ago

I hope someone can really help me out as i really want to make a nice channel. I’m going to start getting some footage of high level play of ssf4 ae in New York’s Chinatown Fair. In the future i will also have high level play of other games such as Arcana Heart 3, Marvel 3, Kof 13 etc. so thanks to anyone willing to help me out.